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Full-Text Articles in Physical Sciences and Mathematics
Quaternary Evolution Of The Colorado River At Lees Ferry, Arizona, William Scott Cragun
Quaternary Evolution Of The Colorado River At Lees Ferry, Arizona, William Scott Cragun
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
A well-exposed suite of Colorado River fill terraces preserved at Lees Ferry records the oscillating history of this major river superimposed on its overall downcutting of the Colorado Plateau. Detailed mapping, sedimentology, cross-sectional surveys, and the use of two geochronometers have been used in order to establish a detailed chronostratigraphy for the area. Eight distinct deposits have been identified along the Colorado River (Ml -M7, and S3), and four deposits have been identified along the Paria River (Pl -P4).
Geochronology of six of these deposits using optically stimulated luminescence and cosmogenic 10Be exposure techniques indicates a long-term average bedrock …
Effects Of Quaternary Climate Change On Tributary Sedimentation And Geomorphology In Eastern Grand Canyon, Benjamin D. Dejong
Effects Of Quaternary Climate Change On Tributary Sedimentation And Geomorphology In Eastern Grand Canyon, Benjamin D. Dejong
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Climate variability has had a dramatic impact on eastern Grand Canyon tributaries over the past ~100 ky. This is readily observed in the Lava Chuar and Comanche catchments, which host well preserved colluvial remnants and river terraces that resulted from several climate-induced cycles of aggradation and incision. This study investigates these climate responses using surveying, sedimentology, and luminescence geochronology methods to investigate the mechanisms and timing of their deposition.
The survey data demonstrate that the concavity of terrace treads is lower than modern drainages. The sedimentology suggests the prevalence of stream-flow reworking of debris flow deposits and portrays an expected …